Western Digital this morning began shipping the 640GB Scorpio Blue, one of the first drives above 500GB to fit in most notebooks. It uses two 320GB platters to reach its capacity while still measuring 9.5mm thick and thus thin enough to fit in particularly slim portables like the MacBook Pro. As a Blue series drive, it's aimed at the mainstream and spins at 5,400RPM with an 8MB cache.

The SATA II drive is selling today as a stand-alone upgrade for $149. Western Digital also supplies hard drives for computer manufacturers but hasn't named any customers for the hard drive upgrade.